[FEATURE] Be aware of empty packages for certain python versions

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I’m always frustrated when […]

Some packages on conda-forge are empty for specific python versions (one example here is dataclasses) as they contain features added to later python versions. The empty packages were added since the package that depends on them could otherwise not be noarch: python. Currently, Grayskull still recommends skipping those packages for the python versions where they aren’t needed anymore, even if the packages are actually empty.

One example here is the output of transformers:

{% set name = "transformers" %}
{% set version = "4.3.3" %}


package:
  name: {{ name|lower }}
  version: {{ version }}

source:
  url: https://pypi.io/packages/source/{{ name[0] }}/{{ name }}/transformers-{{ version }}.tar.gz
  sha256: 48d6cc3ab40c901b9ce803d3b445ff88f023150dde7b36bf834829bca759b7fd

build:
  number: 0
  skip: true   # [py2k]
  entry_points:
    - transformers-cli=transformers.commands.transformers_cli:main
  script: {{ PYTHON }} -m pip install . -vv

requirements:
  host:
    - pip
    - python
  run:
    - dataclasses  # [py<37]
    - filelock
    - importlib-metadata  # [py<38]
    - numpy >=1.17
    - packaging
    - python
    - regex !=2019.12.17
    - requests
    - sacremoses
    - tokenizers >=0.10.1,<0.11
    - tqdm >=4.27

test:
  imports:
    - transformers
    - transformers.benchmark
  commands:
    - pip check
    - transformers-cli --help
  requires:
    - pip

about:
  home: https://github.com/huggingface/transformers
  summary: State-of-the-art Natural Language Processing for TensorFlow 2.0 and PyTorch
  license: Apache-2.0
  license_file: LICENSE

extra:
  recipe-maintainers:
    - ADD_YOUR_GITHUB_ID_HERE

Describe the solution you’d like A clear and concise description of what you want to happen.

Grayskull should be aware of empty packages and not add a skip statement, even if upstream demands it.

Describe alternatives you’ve considered A clear and concise description of any alternative solutions or features you’ve considered. None

Additional context Add any other context or screenshots about the feature request here.

It might be nice to have this in a database that is also linked in the docs. I have opened https://github.com/conda-forge/conda-forge.github.io/issues/1270 to reflect this.

[BastianZim]

I will, but so far it’s actually only dataclasses and typing: https://conda-forge.org/docs/maintainer/knowledge_base.html#empty-python-packages

Another candidate would be typing_extensions but the maintainers are quite busy and haven’t replied to me yet and importlib_metadata which was planned but not finished yet.

Edit: Typing_extensions should be installable under all python versions but has some edge cases so it might be better to keep it off the list.

[marcelotrevisani]

You can add them on this issue, next month I will be more active in developing grayskull again. So, if you have a collection of those things please add them here and I will pick it up 😃

Thanks!